Nanoscale Polydopamine (PDA) Meets π-π Interactions: An Interface-Directed Coassembly Approach for Mesoporous Nanoparticles

Well known for the adhesive property, mussel-inspired polydopamine (PDA) has been shown to enhance performance in a wide range of adsorption-based applications. However, imparting porous nanostructures to PDA materials for enhanced loading capacities has not been demonstrated even when surfactants were present in the synthesis. Herein, we report on the preparation of mesoporous PDA particles (MPDA) based on the assembly of primary PDA particles and Pluronic F127 stabilized emulsion droplets on water/1,3,S-trimethylbenzene (TMB) interfaces. The key to the formation of this new type of the MPDA structure is the full utilization of the pi-pi stacking interactions between PDA structures and the pi-electron-rich TMB molecules. Remarkably, this method presents a facile approach for MPDA particles with an average diameter of similar to 90 nm, slit like pores with a peak size of similar to 5.0 nm as well as hollow cavities. When used as the adsorbent for a model dye RhB, the MPDA particles achieved an ultrahigh RhB adsorption capacity of 1100 mu g mg(-1), which is significantly higher than that for the PDA-reactive dyes with Eschenmoser structure. Moreover, it was demonstrated that the cavity space in MPDA can facilitate high volumetric uptake in a capillary filling/stacking manner via the pi-pi interactions. These developments pave a new avenue on the mechanism and the designed synthesis of functional PDA materials by organic-organic composite assembly for advanced adsorption applications.